This invention relates to a system and to a method for maintaining a swimming pool cover drained of accumulated precipitation.
In temperate climates swimming pools are generally covered during the winter season with a synthetic resin (e.g., vinyl) cover to maintain the cleanliness of the water and to thereby minimize the need for repainting the pool walls and bottoms. So maintaining the cleanliness of the water also obviates the necessity of cleaning the water with heavy doses of chemicals at the beginning of each swimming season. An additional cover, exemplarily the form of a stretch mesh, is sometimes used to prevent leaves and other airborne materials from settling on top the plastic pool cover.
Water which collects on any type of solid pool cover from rainfall and snowfall is pumped off conventionally by a small pump resting on top of the plastic cover. This procedure is recommended by various cover manufacturers and pool supply vendors. Generally, such a pump is connected to an electrical power supply by a user upon the accumulation of a predetermined amount of water on the pool cover, water in excess of this predetermined amount being considered hazardous to the integrity of the cover. Such a procedure is obviously time consuming and tedious.
One possible method for automatically draining accumulated precipitation from a fluid trap in a swimming pool cover comprises the use of a float assembl. Such a method, however, is unsatisfactory owing to the instability of the pool cover as it lies on top of the water and further owing to the "sinking in" of items located on the cover.
Another technique for automatically draining a swimming pool cover includes the use of an electronic water sensing device to control operation of a pump. Such a device is also susceptible to the "sinking in" problem and to the fact that a pump is generally unable to drain a reservoir completely. Accordingly, the electronic water sensing device could be disposed in a small area of water on the swimming pool cover and would continue to operate the pump even though the fluid inlet of the pump was not in communication with the small area of water in which the sensing device was located.
U.S. Pat. No. 4,505,643 to Millis et al. discloses a system for pumping water between a swimming pool or other reservoir and a filter. The control circuit for the pump includes an intermittent actuator for intermittently producing a pump signal with a selectable first duration, e.g., thirty minutes and a selectable first periodicity, e.g., twenty-four hours. A low or abnormal pressure shutdown device terminates operation of the circulating pump unless a circulation fluid pressure attains a preselected pressure level within a preselected second time duration, preferably two minutes. Accordingly, a circulating pump system in accordance with the disclosure of U.S. Pat. No. 4,505,643, Millis et al. operates for the entire first duration unless a low pressure condition is detected during the second, shorter, interval.
U.S. Pat. No. 4,318,421 to Ward is directed to a float control syphon valve for a swimming pool cover. The valve includes cooperating male and female valve members, one of which members is coupled to a float body effectuating the alternate engagement and disengagement of the valve members in response to the level of water accumulated in the swimming pool cover. Such a control syphon valve is not practical insofar as it will operate effectively only if there is a large quantity of water on the pool cover and the drainage point is lower than the level of the cover.
U.S. Pat. No. 3,579,657 to Gurrieri discloses a device for pumping water from a swimming pool cover. The pumping device includes a first unit located on a swimming pool cover, the first unit having a float valve opened by water which has accumulated on the cover. A second unit is provided at a pool skimmer and is connected to the float valve so that water from the cover is conducted to an inlet of a pump in the pool's circulation system. A disadvantage of the device disclosed in U.S. Pat. No. 3,579,657, Gurrieri is that it is inapplicable in most cases due to a removal of the pool's circulation pump and the replacement of water in the interconnecting lines with antifreeze during the winter months. Moreover, closed pools generally do not have skimmers in operation. The method of U.S. Pat. No. 3,579,657, Gurrieri is evidently costly and prone to suction loss and clogging by leaves.
U.S. Pat. No. 3,184,764 to West is directed to a swimming pool cover provided in a central region with a screen overlying a drain opening. Such a drainage system is not adaptable to pre-existing pool covers.
U.S. Pat. No. 2,810,350 to MacWilliams is directed to a method for priming a pump and discloses an automatic pumping system having a gravity operated check valve in a discharge pipe, which check valve is closed by water pressure in the discharge pipe when there is no flow. Upon the cessation of water flow, the check valve operates a check valve switch to shut down the pump.
The object of the present invention is to provide an improved system and an improved method for maintaining a swimming pool cover drained of accumulated precipitation.
Another, more particular, object of the present invention is to provide such a method and such a system which operate automatically, without the need for human intervention.
Another particular object of the present invention is to provide such a method and such a system which conserves energy and extends the useful lifetime of the operating parts.